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Unidentified Fire On Board (OGHFA SE)
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|Content source:||Flight Safety Foundation|
|Human Factors Aspects||Complacency, Situational Awareness, Stress, Airmanship|
|Flight Phase||Cruise, Descent, Landing|
|Operator's Guide to Human Factors in Aviation|
| Situational Example
|Unidentified Fire On Board|
1 The Incident as a Situational example
You are the first officer on a scheduled continental flight that departs normally. About 30 minutes after departure, a louvered panel at the bottom of the cockpit door is accidentally kicked from its mounts and falls to the floor.
An hour and a half into the flight — early in the evening — the three circuit breakers located on a rear cockpit wall panel and associated with the aft lavatory’s flush motor trip in rapid succession.
- What is the pilots’ reaction?
The captain makes two consecutive unsuccessful attempts to reset the circuit breakers.
Ten minutes later, a passenger seated in the last row asks the no. 3 flight attendant to identify a strange odor. She takes a fire extinguisher and sees that a light grey smoke has filled the aft lavatory; however, she sees no fire.
Once advised, the chief flight attendant instructs the no. 2 flight attendant to inform the captain and then to assist the no. 3 flight attendant in moving the passengers forward. The chief flight attendant then takes a fire extinguisher and proceeds to saturate the lavatory with carbon dioxide by spraying the paneling and the seam from which smoke is seeping, as well as the lid of the trash bin.
- What would the next move be?
Upon being notified of the situation, the captain orders you to inspect the lavatory. You leave the cockpit without smoke goggles or a portable oxygen bottle and cannot get to the aft lavatory because the smoke has spread over the last rows of the aircraft. The chief flight attendant then relates what he has seen and says that he has not been able to determine the source of the smoke.
Fifteen minutes into the incident, you go back to the cockpit and advise the captain that it would be better to land. You do not tell him that the chief flight attendant has told you that the fire is not in the trash bin. However, before the captain can respond, the chief flight attendant comes to the cockpit and tells him not to worry, saying, “I think it’s going to be easing up.” You look back into the cabin and see that it is starting to clear. The captain directs you to go back and gives you your smoke goggles.
Shortly thereafter, the chief flight attendant confirms that the smoke is clearing.
- What is the probable source of the fire?
The captain believes the fire was in the lavatory trash bin and that the fire is out; therefore, he decides not to descend.
In the meantime, you return to the aft lavatory and decide not to open the lavatory door when you discover that it feels hot to the touch. You return to the cockpit and tell the captain, “I don’t like what’s happening. I think we’d better go down, okay?” The captain concludes that you believe the fire is out of control.
Meanwhile, the aircraft is experiencing a series of electrical malfunctions. In a matter of minutes, the master warning light illuminates and annunciator lights indicate that the emergency AC and DC electrical buses have lost power.
A mayday call is made. The aircraft is 25 nm (46 km) from the destination and is cleared to descend to 5,000 ft. The approach controller alerts the airport emergency services personnel that the airplane has electrical problems and that there is smoke or fire in the aft lavatory. However, they are not informed of the number of passengers or the amount of fuel aboard the aircraft.
The smoke in the aircraft moves forward, filling the cabin and cockpit. The captain flies the descent wearing smoke goggles and his oxygen mask. During the latter stages of the descent, he has difficulties seeing the instruments because of the smoke in the cockpit and the perspiration that is causing his smoke goggles to steam up. You choose not to use smoke goggles but don your oxygen mask. The cockpit door is left open throughout the descent.
During the descent, the spoiler/speed brake handle is inadvertently moved to the full aft ground position. The cabin crew briefs the passengers on the emergency evacuation, distributes wet napkins and tells the passengers how to open the overwing emergency exits.
After initial level-off at 3,000 ft, the captain orders you to depressurize the aircraft in preparation for landing. You comply and select the air conditioning and pressurization packs off. It is not required by the emergency procedures, but the captain thinks the packs are “feeding the fire.” In an effort to clear the smoke, he opens and closes his sliding window several times during the final stage of the flight.
The horizontal stabilizer trim system is inoperative, so the captain extends flaps incrementally, allowing the airspeed to stabilize at each flap position as he slows to approach speed. After touchdown 10 minutes later, maximum braking is applied. The three flight attendants and 18 passengers use the five opened emergency exits to evacuate. The pilots attempt to enter the cabin and assist the evacuation but are driven back by smoke and heat. After they exit through the cockpit windows, the cabin bursts into flames, and 23 passengers perish in the fire.
2 Data, Discussion and Human Factors
Analyses of in-flight fires have led to the conclusion that the major difficulties are the detection, localization and identification of the severity of the fire. Even when initial detection evidence is available from sensors or human observation, localization of the fire’s source and identification of the severity of the incident are often delayed or inaccurate. These delays result in less time available to make a safe landing.
In this accident, the flight and cabin crews failed to locate the origin of the fire. Although the investigation could not draw any positive conclusion as to the precise point of origination of the fire, evidence indicates that the fire propagated through the lower part of the amenities section of the lavatory vanity. Because of the direction of the airflow in that area, smoke fumes and hot gases were vented overboard and pulled away from the passenger cabin, allowing the fire to burn undetected for almost 15 minutes until it finally penetrated the sidewall and ceiling of the lavatory.
When the circuit breakers tripped, there was no reason, based on their training, for either pilot to surmise an emergency capable of comprising the safety of the aircraft. From the passengers’ standpoint, it can be argued whether the captain should have requested an inspection of the lavatory to ascertain, if possible, the reason for the failure of the circuit, which might have led to an early opportunity to discover the fire.
Initial actions taken by the cabin crew when the smoke was discovered were inadequate to assess quickly the origin and scope of the fire; they never opened the door of the sink compartment to inspect the trash chute and container, and did not use the fire axe to obtain access to the fire.
Since the chief flight attendant and the first officer were not able to determine the location of the fire, they were not able to assess its severity. Consequently, they provided the captain with an inadequate assessment of the fire’s severity.
After the first inspection by the first officer, the captain received a series of optimistic reports from both the chief flight attendant and the first officer concerning the smoke conditions in the aft cabin area. The captain correctly directed the first officer to go aft to reassess the situation. As a result, about 5 1/2 minutes elapsed between the time the no. 2 flight attendant told the captain there was a fire and the decision to begin the emergency descent. Although accident investigations agree that there is a need to evaluate the situation before deciding on an emergency action, the time taken to make the decision in this accident appeared excessive.
The investigation report said that an emergency descent should have been initiated as soon as it became evident that the fire had not been visually located and could not be attacked directly with extinguishing agent. This might have saved three to five minutes, possibly allowing complete evacuation of the aircraft.
Once the decision to descend was made — and considering the conditions during the descent, which included a hostile cockpit environment, use of rudimentary instruments, inoperative horizontal stabilizer trim, accumulation of smoke, heat and toxic gases, and induced stress — the captain exhibited outstanding airmanship.
The flight attendants’ initiative to distribute wet towels to the passengers, together with the appropriate briefing of the passengers contributed to the rapid evacuation of some of the passengers.
3 Prevention Strategies and Lines of Defence
Fire has killed hundreds of crewmembers and passengers on many different airplanes. Accident investigations have shown that hesitating in declaring an emergency can mean the difference between life and death. As a fire spreads, it can render flight controls and primary flight instruments unserviceable and can generate intense heat and dense toxic fumes.
An aircraft fire is difficult to contain because the crew often cannot reach the source. While assuming the fire is out, it can spread behind the numerous panels. Also the place where smoke emerges into the cabin may be very different from the source of the fire.
It is important that the crew gets the correct things done first. Protection, clear communication and prompt action to get the airplane safely on the ground and a quick evacuation after landing are vital.
In case of reported fire or smoke on board:
- Protect yourself — don an oxygen mask and, if needed, smoke goggles.
- Take rapid and aggressive action to identify the source and severity of the fire.
- Immediately declare an emergency if the source and severity of the fire are not positively and quickly determined or if there is no assurance that the fire can be extinguished quickly.
- Prepare for an emergency landing within the shortest time possible.
- Ensure regular communication between flight crew and cabin crew about the following:
- Fire situation — whether or not the source of the fire is known, and whether or not the fire is contained.
- Smoke situation — whether or not the source of the smoke is visible, and the type of smoke.
- Fire fighting actions.
- Time before landing, to enable cabin crew to take positions for evacuating the aircraft.
- Passenger situation.
- Cabin crew should:
- Advise the flight crew.
- Protect themselves before approaching a fire.
- Fight the fire and try to contain it.
- Never assume a fire is out unless the source had been positively identified and cross-checked to be out.
- Passenger protection and crowd control:
- Seat passengers away from the source of fire or smoke, if possible.
- Do not activate any passenger oxygen systems.
- With smoke in the cabin, advise passengers to keep their heads low.
- Emergency approach and landing:
- Ask maximum assistance from air traffic control.
- If electrical systems are functioning normally, consider an automatic approach and landing, especially if there is dense smoke in the cockpit.
- Request maximum runway lighting for improved visibility.
- After landing, evacuate the airplane without delay.
- Flight and cabin crews must receive adequate training, including:
- Fire-fighting courses
- Circuit-breaker resetting policy
4 Key Points
In this situational example, a fire is detected by a flight attendant during cruise. The first officer is sent to inspect the fire but does not immediately assess the criticality of the fire. An emergency descent is initiated. During evacuation, a flash fire engulfs the airplane interior. The probable causes of the accident were the fire of undetermined origin, an underestimate of the fire severity and misleading information about fire progress presented to the captain. The time taken to evaluate the nature of the fire and to decide to initiate an emergency descent contributed to the severity of the accident.
The key to successful management of in-flight fire and smoke events is the early detection of the fire and the identification of its severity.
In case of fire, flight crews should:
- Take immediate and aggressive action to determine the source and severity of the fire; and,
- Begin an emergency descent for landing or ditching if the source and severity of the fire are not positively and quickly determined or if there is no assurance that the fire can be extinguished quickly.
Cabin crew should recognize the urgency of accurately informing flight crew of the location, source and severity of any fire or smoke.
Flight and cabin crew shall be knowledgeable of the proper methods of aggressively attacking a cabin fire.
5 Associated OGHFA Material
The following provide additional information:
6 Additional Reading Material
- Blomberg, R.D.; Bishop E.W.; Hamilton J.W.; Dunlap and Associates; Custer, R.L.P. Worcester Polytechnic Institute, Technology Assessment for Aircraft Command in Emergency Situations, National Technical Information Service, Springfield, Virginia, U.S.; 22161, 1988.
- Cox, J.M. Reducing the Risk of Smoke and Fire in Transport Airplanes: Past History, Current Risk and Recommended Mitigations.